Hot on the heels of a recent DailyTech
blog post concerning finding habitable exoplanets, a group of astronomers
comprised of professor Svetlana Berdyugina of the Swiss Federal
Institute of Technology, Zurich and Andrei Berdyugin and Vilppu
Piirola of the Tuorla Observatory at the University of Turku in
Finland observed light reflected from the atmosphere of a planet
orbiting a star approximately 60 light years from Earth.
The star and planet under scrutiny are
known as HD189733 and HD189733b, respectively. The exoplanet was
discovered in 2005 by Doppler spectroscopy. Astronomers were to
infer the duration of orbital cycles and the probable size of a
planet via Doppler spectroscopy, but hard data like orbital
orientation and physical composition are much more difficult.
Previous findings likened the planet to a hot Jupiter, orbiting very
close to its star.
The astronomers used the 60cm KVA
telescope, which resides in La Palma, Spain, by remote control to
make their observations. The telescope is operated by Tuorla
observatory by agreement with the Royal Swedish Academy of Science to
which it belongs, and was modernized by Finnish scientists.
Rather than directly observing the
light reflected from the planet's atmosphere, the group used a method
similar to polarized glasses. Extraneous light was filtered from other sources and the reflection
of HD189733's light from the atmosphere of HD189733b became visible, similar to the
way we observe the sun's light reflecting off the surface of the
moon.
The light reflected from HD189733b
indicates that the atmosphere surrounding the planet is considerably
larger than the planet itself, in the area of 30% or more, probably
due to the heat of orbiting so closely to its star. Other data
gathered seems to allude to the atmosphere being made up of very
small particles such as atoms, molecules, tiny grains of dust and
possibly water vapor. An atmosphere of this composition would
effectively scatter blue light in the same way as Earth's.
The group has published their
observations in a paper titled First Detection of Polarized Scattered
Light From an Exoplanetary Atmosphere (PDF).
